1. Field of the Invention
The present invention relates to carton assembling method and equipment for sucking and thereby taking out flatwise-folded cartons one by one from a magazine by means of suction cups of a rotative transfer mechanism, then unfolding each carton in a square shape while transferring it downward along a rotative path, and supplying the thus-unfolded carton to an encasing machine by means of a conveyance mechanism.
2.(Description of the Prior Art)
According to conventional carton assembling method and equipment of this type, for example as disclosed in Japanese Patent Laid Open No. 60420/86, there is provided a rotative transfer mechanism of a construction wherein three planetary gear trains are engaged with a fixed gear communicating with a drive source and a suction cup is attached to an outer-end gear of each such planetary gear train, and also provided is a conveyance mechanism of a construction wherein a large number of partition plates are erected on a belt conveyor at equal intervals each corresponding to the width of each carton which belt conveyor is driven in synchronism with the above rotative transfer mechanism. Each planetary gear train rotates along the outer periphery of the fixed gear, causing each suction cup to move rotatively downward along a hypotrochoid path, whereby cartons are sucked and taken out successively from the magazine. Folded edges of each carton are brought into sliding pressure contact with the partition plates which are moving horizontally at constant speed, thereby unfolding the carton gradually, then the suction is released and the front and rear faces of the carton are held between adjacent partition plates. In this state the carton is transferred to an encasing machine while being kept upright.
However, in such conventional carton assembling method and equipment, each carton unfolded on the conveyance path and held squarely by the partition plates cannot be unfolded exactly in a square shape because the carton is under the action of a continuous folding tendency which tries to return to the folded direction. So in the event of even a slight dimensional error between the width of the carton and the spacing of adjacent partition plates for conveyance to the encasing machine, the carton will be deformed into parallelogram due to the above-mentioned action, thus causing the problem that a squarely unfolded carton is not always obtainable as a product.
In the above conventional method and equipment, moreover, not only it is difficult to adjust the timing between the moving path of folded edges of each carton and the horizontal movement of partition plates, but also since the carton is introduced into the space between partition plates at a vertex part of a generally triangular hypotrochoid path, it is impossible to obtain a sufficient time to unfold the carton completely squarely and so the best unfolding condition cannot be expected. This is apparent from the disclosure of Japanese Patent Laid Open No. 26833/84 wherein the carton introducing vertex part of the hypotrochoid path is changed into a generally U shape by means of a cam mechanism to approximately double the carton introducing time and there is made a high speed operation. But the equipment disclosed therein involves the problem that the internal structure of a rotative transfer mechanism is very complicated.
The construction disclosed in the foregoing Japanese Patent Laid Open No. 60420/86 also involves problems. More particularly, since each carton is conveyed to the encasing machine by means of the belt conveyor while its flaps are projected in directions perpendicular to the conveyance direction, not only it is impossible to reduce the width of the belt conveyor but also a contents charging conveyor of the encasing machine cannot be disposed in close proximity to the cylindrical portions of the cartons on the conveyor, resulting in increased size of the entire equipment. Besides, a contents charging pusher disposed so that it can protrude and retract with respect to the cylindrical portion of each carton, is required to be longer in stroke by the length corresponding to the projecting length of the flaps, thus resulting in increased time required for the charging of contents.
In the above prior art, moreover, since contents are charged into each carton while the flaps are kept projected in directions perpendicular to the conveyance direction, if the flaps are inclined inwards even slightly, they will be rolled inside in charging the contents, resulting in that the contents are not exactly charged into the carton.